Multi-spot laser surgical probe using faceted optical elements

ABSTRACT

In particular embodiments of the present invention, an optical surgical probe includes a handpiece configured to optically couple to a light source and a cannula at a distal end of the handpiece. The probe further includes at least one light guide within the handpiece. The light guide is configured to carry a light beam from the light source to a distal end of the handpiece. The probe also includes a multi-spot generator in the cannula that includes a faceted optical adhesive with a faceted end surface spaced from a distal end of the light guide. The faceted end surface includes at least one facet oblique to a path of the light beam. In some embodiments, the probe also includes a high-conductivity ferrule at the distal end of the light guide. In other embodiments, the cannula is formed from a transparent material.

RELATED APPLICATIONS

This application claims priority to U.S. provisional application Ser.No. 61/521,447, filed on Aug. 9, 2011, the contents which areincorporated herein by reference. This application is related toco-pending U.S. patent application Ser. No. 12/959,533, filed on Dec. 3,2010, and commonly assigned with the present Application.

FIELD OF THE INVENTION

This invention relates to optical surgical probes and, moreparticularly, to a multi-spot laser surgical probe using faceted opticalelements.

BACKGROUND OF THE INVENTION

Optical surgical probes deliver light to a surgical field for a varietyof applications. In some applications, it may be useful to deliver lightto multiple spots in the surgical field. For example, in pan-retinalphotocoagulation of retinal tissue, it may be desirable to deliver laserlight to multiple spots so as to reduce the time of the pan-retinalphotocoagulation procedure. Various techniques have been employed toproduce multiple beams for a multi-spot pattern. For example, oneapproach uses a diffractive beam splitter element to divide an incomingbeam into multiple spots that are coupled into multiple optical fibersthat deliver the multiple spots to the retina. But it is also desirableto have a multi-spot generator that can be placed at a distal end of theoptical surgical probe to more easily produce multiple spots from asingle input beam, so that the multi-spot generator can more easily beused with existing laser sources without the need for additionalcomponents to align the laser surgical probe with the sources.

Difficulties can arise in the use of a diffractive beam splitter elementat a distal end of the optical surgical probe. As one example, adiffractive beam splitter element produces a multitude of higherdiffraction orders, and while these orders are relatively lower in lightintensity as compared to the primary spot pattern, they may not alwaysbe negligible in terms of their effects. As another example, adiffractive element may not perform identically in different refractivemedia. For example, if the diffractive beam splitter element is placedinto a medium other than air, such as saline solution or oil, therecessed portions of the microscopic surface relief structure of thediffractive beam splitter element can be filled with material having adifferent refractive index than air, which can ruin the spot pattern. Asyet another example, the spacing between the spots can vary fordifferent wavelengths, which can be problematic when an aiming beam isof a certain color while a treatment beam is of a different color.Lastly, diffractive elements are frequently expensive and difficult toproduce, and this is particularly the case when the diffractive elementmust be constructed to fit into a small area, such as a distal tip of asurgical probe for surgical instruments that are 23-gauge or smaller.Thus, there remains a need for an optical surgical probe that canproduce multiple spots at a target area using optical elements at adistal end of the surgical probe.

BRIEF SUMMARY OF THE INVENTION

Particular embodiments of the present invention provide a thermallyrobust optical surgical probe including a multi-spot generator with afaceted optical adhesive element. In particular embodiments of thepresent invention, an optical surgical probe is includes a handpiececonfigured to optically couple to a light source and a cannula at adistal end of the handpiece. The probe further includes at least onelight guide within the handpiece. The light guide is configured to carrya light beam from the light source to a distal end of the handpiece. Theprobe also includes a multi-spot generator in the cannula that includesa faceted optical adhesive with a faceted end surface spaced from adistal end of the light guide. The faceted end surface includes at leastone facet oblique to a path of the light beam. In some embodiments, theprobe also includes a high-conductivity ferrule at the distal end of thelight guide. In other embodiments, the cannula is formed from atransparent material.

Other objects, features and advantages of the present invention willbecome apparent with reference to the drawings, and the followingdescription of the drawings and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a multi-spot generator with a highly thermallyconductive ferrule according to a particular embodiment of the presentinvention;

FIG. 2 illustrates a multi-spot generator with a transparent cannulaaccording to a particular embodiment of the present invention; and

FIG. 3 illustrates a multi-spot generator with a transparent cannulaaccording to an alternative embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EXEMPLARY EMBODIMENTS OF THEINVENTION

Co-pending U.S. application Ser. No. 12/959,533, filed on Dec. 3, 2010and commonly assigned with the present Application, describes amulti-spot optical surgical probe using faceted optical adhesive.Various embodiments of the present invention provide additional featuresto facilitate the use of faceted optical adhesive in optical surgicalprobes. In particular, certain embodiments of the present inventionprovide a thermally robust optical surgical probe using faceted opticaladhesive. As described in detail below, particular embodiments of thepresent invention incorporate o additional features to reduce thelikelihood that “hot spots” will develop in the surgical probe thatcould cause the faceted optical adhesive or the adhesive joining theferrule and the cannula to degrade and/or fail.

In certain embodiments of the present invention, a ferrule locatedwithin the distal end of the probe is modified to improve its ability toconduct heat away from the distal tip of the probe. The firstmodification is to change the material from the typically-used,low-thermal-conductivity stainless steel to a material with a muchhigher thermal conductivity such as copper or silver. The ferrulematerial need not necessarily be biocompatible since it is physicallyisolated from the outside of the probe. This permits the selection of anon-biocompatible material such as copper or silver that has much higherthermal conductivity than any available biocompatible materials. Thehigher thermal conductivity enables more efficient conduction of heataway from the distal end of the probe. The second modification is to addto the cylindrical ferrule a distal side-shield that prevents lightreflected off of the adhesive facets from illuminating and beingabsorbed by the cannula. Instead, reflected light illuminates and issubstantially absorbed by the high-thermal-conductivity ferrule thatefficiently conducts the heat away from the distal end of the probe.

In an alternative embodiment of the present invention, the absorptivecannula is replaced with a transparent cannula that transmits reflectedlight from the adhesive facets into the ambient region outside of thecannula. This results in a significant reduction in the temperature ofthe distal end of the probe. Since high intensity transmitted lightdirected toward the surgeon may interfere with his view of the retina,various means are available to block or dissipate this light, includinga reflective, diffusive or translucent layer on the outside of thetransparent cannula and an opaque cylindrical cannula outside of thetransparent cannula and physically separated from it by an insulatingair gap. This opaque cannula need not necessarily be made from a highlythermally conductive material but it can be made from a stiff and strongmaterial such as stainless steel which provides added structuralstrength to the distal end of the probe.

FIG. 1 illustrates a multi-spot generator 100 according to a particularembodiment of the present invention suitable for placement at a distalend of an optical surgical probe. In the depicted embodiment, a facetedoptical adhesive 104 having a ball lens 106, such as a sapphire balllens, is located within a cannula 108. Within the cannula 108 is ahigh-conductivity ferrule 110 holding an optical fiber 112. The opticalfiber 112 delivers light, such as laser light, from an illuminationsource (not shown).

The high-thermal-conductivity ferrule 110 (hereinafter referred to as“high-conductivity ferrule”) is formed from a material with a thermalconductivity significantly higher than the stainless steel materialordinarily used in optical surgical probes, which is typically around 15W/m-K. For purposes of this specification, “high-conductivity” willrefer to materials having thermal conductivity in excess of 100 W/m-K.Suitable examples include copper (conductivity of 372 W/m-K), sterlingsilver (410 W/m-K), or pure silver (427 W/m-K). Because thehigh-conductivity ferrule 110 is encapsulated within the cannula 108 bythe faceted optical adhesive 104, the high-conductivity ferrule 110 neednot be made of a biocompatible material, which allows consideration ofhigh-conductivity materials that are not ordinarily used in opticalsurgical probes.

The high-conductivity ferrule 110 includes a side-shield 114 extendingdistally past the optical fiber 112. The side-shield 114 is oriented toreceive light reflected from facets of the faceted optical adhesive 104.While reflections from the faceted optical adhesive 104 are relativelylow in energy compared to the incident beam (approximately 5% ofincident energy), such reflections can nonetheless produce “hot spots”on the cannula 108. Given that the cannula 108 is ordinarily formed fromstainless steel or other relatively poorly conducting material that isalso not highly reflective, this can result in laser energy beingabsorbed, which in turn creates the potential for excess heat toaccumulate near the faceted optical adhesive 104 or near the adhesivethat bonds the ferrule 110 to the cannula 114 (not shown). This candegrade the performance of the optical surgical probe. The side-shield114 intercepts the reflected beams to prevent them from reaching thecannula, and because the material of the ferrule 110 is highlyconductive, any heat produced by absorption of the reflected beams inthe ferrule 110 is rapidly dispersed, preventing the equilibriumtemperature of the ferrule 110 from being significantly raised.

FIG. 2 illustrates an alternative embodiment of a thermally robustmulti-spot generator according to the present invention. In the depictedembodiment, cannula 108 is formed of a transparent material. Thematerial is preferably biocompatible, but if it is not, the outersurface cannula 108 may also be coated or treated to improvebiocompatibility. The transparent cannula 108 allows the reflected lightto pass through the cannula 108 to avoid forming hot spots. Inparticular embodiments, the cannula 108 is diffusive, so that theescaping light does not form visible light spots that could bedistracting for a surgeon. For example, the surface of the cannula 108could be formed from a translucent material, could be chemically ormechanically frosted (such as by scraping or acid etching), or could becoated with a diffusive coating. In alternative embodiments, the cannula108 is transparent, but surrounded with a reflective coating, such assilver. The reflective coating prevents light from escaping into thesurgeon's field of view while still reflecting the light away from thefaceted optical adhesive 104, allowing the heat to be conducted awayfrom the tip easily. The outer surface of the silver or reflectivecoating can be oxidized or coated to improve biocompatibility.

FIG. 3 illustrates an alternative embodiment of the transparent cannula108. is In the depicted embodiment, an opaque outer cannula 120surrounds the transparent cannula 108. The opaque outer cannula 120 maybe formed from conventional biocompatible materials, and it ispreferably relatively absorptive, although it need not be highlyconductive. The outer cannula 120 and the transparent cannula 108 areseparated by an air gap. The air gap provides thermal insulation betweenthe transparent cannula 108, and the transparent cannula 108 may also beformed from an insulative material like glass. Whatever heat is producedin the outer cannula 120 may be conducted away into other parts of theprobe or the biological material surrounding the outer cannula 120. Thethermal insulation between the outer cannula 120 and the faceted opticaladhesive 104 reduces the likelihood of excess heat from accumulatingnear the faceted optical adhesive 104.

The present invention is illustrated herein by example, and variousmodifications may be made by a person of ordinary skill in the art.Although the present invention is described in detail, it should beunderstood that various changes, substitutions and alterations can bemade hereto without departing from the scope of the invention asclaimed.

1. An optical surgical probe comprising: a handpiece, the handpiececonfigured to optically couple to a light source; a cannula at a distalend of the handpiece; at least one light guide within the handpiece; theat least one light guide configured to carry a light beam from the lightsource to a distal end of the handpiece; a multi-spot generator in thecannula, the multi-spot generator including a faceted optical adhesivewith a faceted end surface spaced from a distal end of the light guide,the faceted end surface including at least one facet oblique to a pathof the light beam; and a high-conductivity ferrule at the distal end ofthe light guide.
 2. The probe of claim 1, wherein the high-conductivityferrule is formed of silver.
 3. The probe of claim 1, wherein thehigh-conductivity ferrule is formed of copper.
 4. The probe of claim 1,wherein the high-conductivity ferrule comprises a side shield shieldingthe cannula from reflected light from the faceted optical adhesive. 5.The probe of claim 1, wherein the high-conductivity ferrule has athermal conductivity of at least 372 W/m-K.
 6. An optical surgical probecomprising: a handpiece, the handpiece configured to optically couple toa light source; a transparent cannula at a distal end of the handpiece;at least one light guide within the handpiece; the at least one lightguide configured to carry a light beam from the light source to a distalend of the handpiece; a multi-spot generator in the cannula, themulti-spot generator including a faceted optical adhesive with a facetedend surface spaced from a distal end of the light guide, the faceted endsurface including at least one facet oblique to a path of the lightbeam,
 7. The probe of claim 6, wherein the transparent cannula istranslucent.
 8. The probe of claim 6, wherein the transparent cannula isfrosted.
 9. The probe of claim 6, wherein the transparent cannulafurther comprises a highly-reflective coating on an exterior of thecannula.
 10. The probe of claim 6, wherein the transparent cannula issurrounded by an opaque outer cannula separated from the transparentcannula by an air gap.